Decomposition of plant material is a fundamental biogeochemical process, integral to ecosystem nutrient cycles. While numerous studies have yielded rich amounts of data describing how plant litter chemical content relates to its decomposition, most focus only on initial chemistry as an indicator of how litter will behave throughout decomposition. This limits our understanding of later stages of decay, which are vital for long-term ecosystem processes and biogeochemical cycling. If litter chemistry does not change in parallel to the initial differences, our ability to predict the later stages of decomposition will be limited. Not only do we have little data measuring late-stage chemistry, there are entire functional groups missing from our understanding, such as cacti. We analyzed changes in leaf and cacti chemistry throughout decomposition from a variety of leaf/cacti species from across multiple ecosystems using archived leaf decomposition samples, as well as a current and ongoing cacti decomposition project. We explored whether diverse plant litter types maintain initial chemical differences throughout decay, remain chemically unique, or if decomposing litter follows different chemical trajectories over the course of decomposition. Further, we investigate how these trajectories relate to leaf and cacti decay rate.
We have collected 43 datasets and have re-analyzed archived litter from a number of completed studies, primarily from Long-Term Ecological Research (LTER) sites, in which some measure of litter chemistry was measured throughout decomposition (i.e., beyond initial chemistry). From the data tested, it seems that all three of our hypothesis are supported. We found that the suite of litter chemical characteristics known to influence decomposition followed consistent patterns throughout decay across systems (e.g., forest, desert, agriculture, etc.) stayed different, and that initial litter chemistry is the main determinant (i.e., they homogenized chemically at a certain point of decomposition). To be able to consistently compare nutrient cycling across ecosystems, cacti decomposition is also being studied to compare and contrast leaf to cacti decomposition. The similar chemistry from the leaf litter will be analyzed in the cacti samples and will aid our understanding of biogeochemical cycling desert ecosystems.